The invention relates to improvements in apparatus for transporting unwound webs of wrapping material, especially for smokers"" products, and more particularly too improvements in apparatus for treating running webs of paper, artificial cork or other flexible sheet material. Such webs are normally drawn off bobbins and can be utilized in filter tipping machines wherein plain cigarettes, cigars or cigarillos (hereinafter referred to as cigarettes) are assembled with filter rod sections to yield filter cigarettes of unit length or multiple unit length.
It is customary to advance a web of so-called tipping paper from a bobbin or another suitable source past a perforating unit which provides the running web with pores or the like in order to render the web permeable to gaseous fluids, i.e., to permit penetration of air into the column of tobacco smoke flowing from the lighted end of a filter cigarette, through the mouthpiece and into the mouth of a smoker. It is also customary to advance successive increments of the running web past (around) a so-called curling device which promotes the tendency of the web to yield uniting bands which can be readily converted into cylindrical or oval envelopes each of which surrounds the mouthpiece and the adjacent end portion of the tobacco-containing part of a plain cigarette.
The web treating action of the curling device is greatly influenced by the nature and/or extent of treatment of the running web ahead of the curling station. The quality of filter cigarettes containing convoluted uniting bands made of a properly or optimally curled web invariably exceeds the quality of filter cigarettes containing uniting bands which are obtained as a result of repeated severing of a poorly curled web of tipping paper. The web which is being advanced toward the curling station is engaged by one or more advancing or transporting devices which not only advance but also tension those successive increments of the running web which advance past the curling station. Moreover, the bobbin which supplies the web (i.e., from which the web is being unwound) is acted upon by a brake.
A curling device can be designed to exhibit a cylindrical surface provided with suction ports which attract succesive web portions or increments trained around a portion of the cylindrical surface. The quality of curling action furnished by such device is dependent upon the nature of treatment to which the running web is subjected upstream of the curling station.
Curling devices at least some of which can be put to use in the apparatus of the present invention are disclosed, for example, in U.S. Pat. No. 3,996,842 granted Dec. 14, 1976 to Klaus-Dieter Ehlich and Heinz-Christen Lorenzen for xe2x80x9cAPPARATUS FOR REDUCING AND EQUALIZING LOCALIZED STESSES IN RUNNING PAPER WEBS OR THE LIKExe2x80x9d.
An object of the invention is to provide a novel and improved apparatus for manipulating running strips, tapes or webs of a sheet material which is to be converted into cylindrical envelopes or the like, for example, in a tipping machine which serves to turn out filter cigarettes.
Another object of the invention is to provide a novel and improved apparatus which employs one or more so-called web curling or rolling devices.
A further object of the invention is to provide novel and improved means for treating a running web ahead or upstream of a curling device.
An additional object of the invention is to provide an apparatus which can be installed in or utilized in conjunction with existing filter tipping machines.
Still another object of the invention is to provide a novel and improved method of manipulating a running web of perforated uniting band material for use in filter tipping machines ahead of the web curling station.
A further object of the invention is to provide a novel and improved web braking and stressing device for use in the above outlined apparatus.
Another object of the invention is to provide a novel and improved combination of an adjustable web curling device and a web monitoring unit for use in the above outlined apparatus.
An additional object of the invention is to provide a novel and improved combination of at least one web curling device, adjusting means for the curling device, and means for advancing the web toward, past and beyond the curling device.
The invention is embodied in an apparatus for treating a running web of flexible sheet material, e.g., a permeable sheet material which has undergone treatment in an apparatus of the type shown in FIGS. 1 and 2 of U.S. Pat. No. 4,281,670 granted Aug. 4, 1981 to Uwe Heitmann et al. for xe2x80x9cAPPARATUS FOR INCREASING THE PERMEABILITY OF WRAPPING MATERIAL FOR ROD-SHAPED SMOKERS"" PRODUCTSxe2x80x9d. The apparatus of the present invention comprises suitable means for advancing the web from a source (such as a bobbin or reel) in a predetermined direction along an elongated path; the advancing means can include a first advancing unit defining a first portion of the path and a second advancing unit defining a second portion of the path downstream of the first portion. The improved apparatus further comprises a magazine or an analogous storage facility defining a third portion of the path between the first and second portions, an adjustable suction-operated web braking device adjacent a fourth portion of the path between the third and second portions, and web curling means adjacent a fifth portion of the path between the fourth and second portions.
At least one of the first and second advancing units can comprise a pair of driven rollers which define a nip for the running web in the respective (first or second) portion of the path.
In accordance with a presently preferred embodiment, the magazine can be installed immediately downstream of the first port ion of the path and can include means for temporary storage of successive lengths of the running web in the form of one or more loops as well as means for varying the length of that portion of the running web which can be stored in the magazine.
The braking device can include means for applying to the web a variable braking force in the fourth portion of the path (i.e., upstream of the curling means), and means for adjusting the braking force. The force applying means can include a roller having a peripheral surface which contacts the web in the fourth portion of the path, and means for rotating the roller in a direction to move the peripheral surface of the roller in the fourth portion of the path counter to the (predetermined) direction of advancement of the web along its path. The arrangement can be such that the second advancing unit is set up to advance the web at a first speed whereas the means for rotating the roller of the braking device is arranged to move the peripheral surface of the roller in the fourth portion of the path at a second speed which is less than the first speed, e.g., at a second speed which is close to zero speed. The peripheral surface of the aforementioned roller of the force applying means can be provided with a plurality of suitably distributed ports, and the running web is trained over a first portion of such peripheral surface, i.e., a second portion of the peripheral surface is out of contact with the running web. The force applying means of the braking device can further include a suction generating device (e.g., a blower or fan having a suction intake) and means for connecting the suction generating device with ports which are provided in the first portion of the peripheral surface.
The just described web braking device can further comprise means for expelling impurities, if any, from the ports in the second portion of the peripheral surface of the roller forming part of the braking device. For example, the impurities expelling means can include a source of compressed gaseous fluid and means (such as axially parallel channels in the roller of the braking device) for connecting the source of compressed gaseous fluid with the ports in the second portion of the peripheral surface.
The roller of the braking device imparts to the fourth portion of the path an arcuate shape.
The apparatus can further comprise means for monitoring the tension upon the running web, particularly the tension which is generated by the second web advancing unit, and means for actuating the aforementioned adjusting means when the monitored tension is outside of a predetermined range.
The roller of the braking device can be provided with axially spaced-apart flanges flanking that portion of the web which is trained over the roller in the fourth portion of the path, namely over that portion of the roller which is provided with the aforementioned ports.
The improved apparatus can further embody that feature which is disclosed in the aforementioned ""842 patent to Ehlich e al., namely means for monitoring the running web to detect the splices which connect successive elongated sections of the web to each other. The apparatus can employ an adjustable curling means, and the latter is adjusted whenever a splice advances along the fifth portion of the path. The curling means can be designed in such a way that it is adjustable between an operative and an inoperative condition, and the splice detecting monitoring means can generate signals which render the curling means inoperative during advancement of detected splices along the fifth portion of the path for the running web.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved web treating apparatus itself, however, both as to its construction and the modes of assembling and operating the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.